This invention relates to fused AZS grain refractory compositions suitable for making ceramically or chemically bonded refractory articles and to the articles so made.
The general concept of rebonding crushed fused AZS grain is well known in the art. Numerous compositions containing crushed fused AZS and other materials have been developed for various end uses. See, for example, U.S. Pat. No. 4,119,472 and the patents cited therein.
The composition disclosed in U.S. Pat. No. 4,119,472 disclosed as being characterized by superior resistance to corrosion by molten glass and alkali in contact therewith and by superior flexure strength at room temperature before and, in many cases, after substantial thermal cycling. The composition of U.S. Pat. No. 4,119,472, in its broadest aspect, consisted of (A) 25-60 wt. % fusion cast AZS refractory coarse grain, (B) 0-38 wt. % fusion cast AZS refractory medium grain, and (C) 30-50 wt. % of at least one component selected from the group consisting of (1) 0-50 wt. % fusion cast AZS refractory fine grain, and (2) 0-30 wt. % at least one constituent selected from the group consisting of (a) alumina being at least 90 wt. % -325 Tyler mesh, at least 98.5 wt. % Al.sub.2 O.sub.3 and not more than 0.5 wt. % Na.sub.2 O, and (b) -325 Tyler mesh chromic oxide being at least 95 wt. % Cr.sub.2 O.sub.3. The refractory composition of U.S. Pat. No. 4,119,472 does not utilize reactive alumina. Despite the improved properties provided by the refractory compositions of U.S. Pat. No. 4,119,472, the need exists for a refractory composition which has higher corrosion resistance to glass and which will have a longer life in glass melting furnaces. This has been accomplished with the refractory compositions of this invention by improving the bonding matrix. Articles made from the refractory compositions of this invention are superior to articles made from prior art compositions in that they have high glass corrosion resistance and still maintain advantageous properties such as thermal cycling capability.